1. The Field of the Invention
This invention relates to oil and gas drilling, and more particularly to apparatus and methods providing a downhole network for transmitting information between downhole drilling components, and from downhole drilling components to the ground's surface.
2. The Relevant Art
MWD (measurement while drilling) involves the transmission of data from downhole drilling components to the earth's surface in real time. Once reaching ground level, the data may be analyzed. The data may be used to adjust drilling parameters, such as drilling direction, penetration speed, and the like. Data may originate from various downhole components, including a bottom hole assembly comprising a drill bit and other components, and from sensors and tools located farther up the drill string. What is lacking are apparatus and methods to effectively link or network various downhole sensors and tools together such that they may communicate with one another, transmit data at high speeds to the ground's surface, or receive commands originating from the ground's surface.
The advantages of computer networks are well known. By interconnecting two or more computers, computing resources, data storage devices, and peripherals may be shared. Data and applications may be seamlessly transferred or accessed between computers connected to the network. Redundant components enable data to be backed up from one computer to another. Moreover, the performance provided by modern networking protocols provides for high-speed bi-directional transmission of data from one location to another. Nevertheless, few if any instances of the prior art teach the integration of a network into a downhole drill string.
U.S. Pat. No. 6,218,959 to Smith describes a system and method for fail-safe communication of information transmitted in the form of electromagnetic wave fronts. These wave fronts propagate through the earth between surface equipment and downhole components. The system comprises two or more repeaters disposed within a well bore such that the two repeaters receive each signal carrying the telemetered information. The repeater that is farther from the source includes a memory device that stores information carried in the signal. A timer device, in the repeater that is farther from the source, triggers the retransmission of the information after a predetermined time period, unless the repeater that is farther from the source has detected a signal carrying the information, generated by the repeater that is closer to the source.
The repeaters taught by Smith are wireless repeaters and would not be suitable for a hardwired network integrated into a drill string. Moreover, the repeaters are used exclusively for receiving and forwarding data signals. These repeaters lack many features, such as the ability to gather data or provide control signals at nodes along the drill string.
U.S. Pat. No. 5,959,547 to Tubel et al. teaches a plurality of downhole control systems interconnected by a network including a server for monitoring and controlling network communications. Each downhole control system is associated with a zone in one or more wells. The downhole control systems communicate directly with each other transferring information and commands as necessary. The downhole server monitors network communications to resolve data collisions and provides supervisory functions. The system taught by Tubel et al. is designed for production well systems and would not function in drill strings.
U.S. Patent Application No. 20030038734 to Hirsch et al. describes a reservoir production control system includes a plurality of wells for producing a reservoir linked to a central computer over a downhole communication network and a surface communication network. Both the downhole and the surface communication networks are wireless communications paths for transmitting downhole data and surface data to the central computer.
Both networks include a series of interconnected tubing or pipe that allows transmission of data over electrically isolated portions of the pipe and tubing. After integrating and analyzing all relevant data and comparing the data with a reservoir model, the central computer initiates changes in a plurality of downhole control devices associated with the wells, thereby optimizing the production of the reservoir. Like the Tubel et al. reference, the system taught by Hirsch et al. is designed for production well systems and would not be suitable for integration into a drill string.
In view of the foregoing, what are needed are apparatus and methods to interconnect downhole-drilling components by way of a high-speed network. Such a high-speed network may enable high-speed data transmission between downhole components, and between downhole components and the ground's surface.
What are further needed are apparatus and methods to acquire or gather data at various points or nodes along the drill string, for transmission along the network.
It would be a further advance to allow control or other signals to be transmitted from the surface to downhole components or tools connected to the network.
It would be a further advance to provide downhole nodes, that not only repeat or amplify a signal, but are also configured to gather data from sensors such as inclinometers, pressure transducers, thermocouples, accelerometers, imaging devices, seismic devices, and the like.